2,6-Diisopropylphenylphosphane: A new, bulky primary phosphane and its mono- and disilylated Si(CH<sub>3</sub>)<sub>3</sub> and Si(CH<sub>3</sub>)<sub>2</sub>-<i>t</i>-Bu derivatives A synthetic, crystallographic, and dynamic NMR investigation
Bibliographic record
Abstract
The bulky primary phosphane 2,6-diisopropylphenylphosphane, DipPH2, has been prepared from 1-bromo-2,6-diisopropylbenzene via the reaction of the Grignard reagent with PCl3. The resulting mixed phosphonous dihalides DipP(Cl,Br)2 are reduced with LiAlH4 to yield the title compound in reasonable yield and on a synthetically useful scale. DipPH2 is also used to prepare the monosilylated derivatives DipPHSi(CH3)3 and DipPH{Si(CH3)2-t-Bu} as well as the disilylated compounds DipP{Si(CH3)3}2 and DipP{Si(CH3)2-t-Bu}2. All products have been fully characterized by IR, mass, and NMR spectroscopy. The crystal structure of DipPH{Si(CH3)2-t-Bu} was determined from single-crystal diffraction data: C18H33PSi, P21/c, Z = 4, a = 8.5768(10), b = 28.104(3), c = 8.1102(4) Å, β = 93.341(3)° (R = 0.0518). Changes in the NMR spectrum of DipPH{Si(CH3)2-t-Bu} were observed over the temperature range 178380 K. Barrier heights were determined from the peak separation at low temperature and the coalescence points: ΔG [Formula: see text] 40 kJ mol1 for C(aryl)P bond rotation and [Formula: see text] 72 kJ mol1 for pyramidal inversion at phosphorus.Key words: crystal structure, 2,6-diisopropylphenyl, bulky substituents, steric congestion, dynamic NMR, primary phosphane, silyl phosphane.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".